A "quadrangle" is a United States Geological Survey (USGS) 7.5-minute map, which are usually named after a local physiographic feature. The shorthand "quad" is also used, especially with the name of the map; for example, "the Ranger Creek, Texas quad map". These maps are one-quarter of the older 15-minute series. On a quadrangle map, the north and south limits are not straight lines, but are actually curved to match Earth's lines of latitude on the standard projection.[clarification needed] The east and west limits are usually not parallel as they match Earth's lines of longitude. In the United States, a 7.5 minute quadrangle map covers an area of 49 to 70 square miles (130 to 180 km2).
Quadrangles that lie on the pole of a body are also sometimes called "areas" instead, since they are circular rather than four-sided.